A method and apparatus for handling the wheel of a motor vehicle wheel unit which thus consists of the wheel itself and a pneumatic tire fitted thereon, on a tire fitting machine in which the wheel to be handled is clamped fast on a rotary base by means of displaceable clamping elements can be found for example in the monty-centuro prospectus from Hofmann Werkstatt-Technik GmbH, Pfungstadt, Germany, imprint 9402449 01.95 or the monty prospectus also from Hofmann Werkstatt-Technik GmbH, Pfungstadt, Germany, imprint 9402445 11.94.
In the procedure involved in fitting a pneumatic tire to a wheel such as a disk wheel, the bare wheel is fixed to the tire fitting machine by means of suitable clamping elements and then the tire is fitted on to the wheel itself by means of the appropriate tools on the fitting machine. To remove a pneumatic tire from a wheel such as a disk wheel the motor vehicle wheel unit consisting of the wheel with tire thereon is secured to the fitting machine by means of the same clamping elements. The tire can then be removed from the wheel by removal tools which are also provided on the machine. The fitting and removal tools can be brought into operation in such a way as to handle the wheel material carefully when dealing with special wheels consisting of light metal or alloy, for example aluminum, magnesium, titanium or alloys thereof.
It will be noted at this point that the term light metal is used herein to denote both light metal and also an alloy thereof as is frequently used for the production of motor vehicle wheels.
The wheel can be clamped in position on the tire fitting machine from the outside or from the inside of the wheel. When the wheel is clamped in position from the outside, clamping elements which are in the form of clamping jaws engage one of the two wheel rim flanges. The clamping elements can be moved in a radial direction in relation to the wheel in order to hold it firmly in position on the machine. When a wheel is clamped from the inside, clamping jaws engage the inside surface of the wheel dish or center.
The clamping jaws which engage the wheel from the inside or from the outside are mounted on radially movable clamping arms or clamping shoes. It is also possible for the wheel to be fixed in position on the machine by means of a clamping arrangement, using one or more clamping cones engaging into the central opening in the disk part of the wheel. That way of fixing the wheel in the fitting machine is similar to that which is used when securing a motor vehicle wheel on the main shaft of a balancing machine for balancing the wheel. A suitable holding assembly which ensures that the wheel is suitably supported at the center thereof can provide for preliminary positioning of the wheel in the tire fitting machine before the wheel is definitively clamped in position. The holding assembly can be of a plate-like configuration and may possibly be of a sprung nature.
In order to ensure that in particular light metal wheel rims of for example aluminum, magnesium, alloys thereof or the like are handled carefully so as not to cause damage to the wheel, rubber or plastic covers or pads may be provided on the clamping jaws of the tire fitting machine. Under the rough operating conditions found in a workshop however those rubber or plastic covers or pads wear away so that in particular light metal wheel rims or paint on a wheel rim may be damaged when the wheel is clamped in place. In many cases it is difficult for the machine operators to ascertain by visual inspection whether they are dealing with a wheel made of light metal or alloy, or a wheel made of steel, as in many cases the paint used on disk wheels is identical.